Luxembourg City is built on dramatic cliffs and gorges. The old town sits on top of the cliffs, and the lower town (Grund) sits in the valley below. Bridges connect them. The Bock Casemates are underground tunnels carved into the cliffs (used as fortifications and bomb shelters). You can tour them and see views from the cliffs. The Grand Ducal Palace is the official residence of the Grand Duke. You can tour it in summer.

The old town is charming with narrow streets, squares, and the Notre-Dame Cathedral. It's small, walkable, and easy to see in a few hours.

Grund (the lower town) is quieter and more residential with riverside cafés and walking paths.

The countryside has castles (Vianden Castle is the most impressive), hiking trails, and small towns. It's pleasant but not particularly exciting.

Luxembourgish food is influenced by French, German, and Belgian cuisine. Expect hearty stews, sausages, and pastries. Luxembourg is expensive (similar to Switzerland).
Luxembourgers are multilingual. Most speak Luxembourgish, French, German, and English. The country is wealthy, multicultural (lots of EU expats), and polite.

Getting around is easy. Luxembourg is tiny. Trains and buses connect Luxembourg City to other towns. Public transportation is free for everyone (residents and tourists).
Luxembourg is expensive. Hostels run $25-40/night. A meal at a restaurant is $15-25. A coffee is $3-5.

When to go: Spring (April-May) and fall (September-October) are mild. Summer (June-August) is pleasant but can be rainy. Winter (November-March) is cold and gray.

Luxembourg is pleasant but not a must-see. If you're nearby and have time, stop for a day. Otherwise, skip it.